As shown in Table 2, the presence or absence of ctDNA was associated with bone marrow involvement (19/19 patients with bone marrow involvement had detectable ctDNA versus 5/8 patients without bone marrow involvement, p=.005, χ2 test), but not with the FLIPI score, the serum LDH level, anaemia, bulky disease, the presence of circulating lymphoma cells (detected by morphology or flow examination) or the β2 microglobulin level. This evidence concerns the gene HLA-G and lymphoma.